Conventional fuel vapor recovery systems used in automotive vehicles typically include a carbon canister used to recover excess fuel vapor generated in the fuel tank. Activated carbon in the carbon canister adsorbs the fuel vapor and temporarily retains the vapor until the canister is purged. When the engine is operating at a predetermined operating state, the fuel vapor adsorbed by the activated carbon is desorbed by introducing air to the canister. The fuel vapor thus desorbed is fed to the engine for utilization in combustion.
Typically, the air used to purge the carbon canister is first filtered by an air filter. Generally, prior art air filters for carbon canisters typically comprise a fiber filter in a housing, with the filter assembly being located in an area on the vehicle that may be exposed to dust, dirt, grime, road salt, and other matter. The inventor of the present invention has found certain disadvantages with these air filters. For example, the filters tend to become prematurely occluded with foreign matter. Thus, these filters must be replaced at frequent maintenance intervals.
Self-cleaning air filters exist, however they generally utilize either a separate air source or a portion of redirected inlet air so as to flush the air filter element by forcing air through the outlet side of the filter element. This generally requires either a separate air source or extensive ducting of the inlet air to redirect the airflow. Other self-cleaning air filters using a wiper may not clean the entire surface of the filter element. Not only are these self-cleaning filters more complex resulting in high production and maintenance costs, but, because the wiper is in constant contact with the filter element, the fibers of the filter element may become frayed.